Closed circuit alarm



April 14, 1942.

w. FOUNTAIN 2,279,394 CLOSE-D CIRCUIT ALARM Filed May 8, 1941 Wi'ZZz'am ATTORNEYS WITNESS Patented Apr. 14, 1942 UNITED :sTArEs PATENT OFF-ICE 2,279,394" v chosen cmcurr' i s WiHiamEountain, Mason, .Mich'.

ApplicationMay 8,1941,-Serial-Nc. 392,561 r 1.0mm. (o1. Haj-s14) This'invention relates to closed circuit'alarms andhas for an object to provide 'a protective system of this typeinwhi'chopening of the closed circuit by any one of a number of intruder .trippe'd switches, or actuation-"of thermostatic breakers, energizes a *normally open alarm circuit, the arrangement being'such"'that the" alarm circuit cannot be again deenergized until the normally closed circuit is again completed and an electromagnetic switch therein reset.

A further object is 'to'provid'e a normally open circuit in the nature ofa wire assembled with; but insulated from, the normallyclosed' circuit;

and adapted to ground"the"electromagnetic" switch and permit energizingofthe alarm circuit in the event a" surreptitious attemptis' made to sever thenormallyclosed circuit wireb'y a With the above and otherobjects in View; the

invention consistsof certain novel details of construction and combinations of parts hereinafter fully described and claimed, it being understood that various modifications may be resorted to within the scope of the appended claim without departing from the spirit or sacrificing any of the advantages of the invention.

In the accompanying drawing forming a part of this specification the figure is a diagrammatic view showing the circuits and electrically operated apparatus of a closed circuit alarm constructed in accordance with the invention.

Referring now to the drawing in which like characters of reference designate similar parts in the View, Ill designate a normally closed circuit that extends around a building or area to be protected and is grounded at one terminal, as shown at II. The circuit includes a plurality of circuit breakers I 2 which may be intruder tripped switches, thermostatic breakers, or other devices adapted to open the circuit when displaced from normal circuit closing position. The circuit is energized from a 110 volt source of current, such as a wire l3 connected to a fuse block or other device.

An electromagnetic switch I 4 is connected be tween the closed circuit and the source of current supply. -The switch i in the nature" of a relay having-one end of its coil connected to the'closed circuit-Ill; Theother end of thecoil is connected-by a wirel5 to'= the armature l6 of the relay'and a wire I! connects'a switch i8 in-parallel with the armature. The armature forms a conductor, as is usual, and when the coil is energized, engages a fixedcontact +9 whichis connected to the switch 'bya conduct'or Wire 20: and is connected" to th source of current by a conductor wire 2+ which includes alow wattage device, sucha'sa-lampZZ. p

switch I 8 maybe a push button switch. When the push'butt'onswitch is closed, even 1110- mentarily; current will-flow through'the wire 2!, wire 20, switch [8, wire" ll,.wire' l5, coil M of the relay"; and closed circuit IWto'the. ground 11. The-"relay coil is thus energized" to move the armature Hi into circuit closing; position with the contact 19' Whereuponcurrent will flow through thewire 2i, contact 19, armature 16, wire' [5, coil I4, and closed circuit ['0 to thefgroundso thatthi's circuit remainsclosed when'jtlie push button switc'his released. 7

A normallyopen" alarm circuit 23- is connected to the ground H. and includes an electrically "op.- erate'd' bell 24, or other alarmdevice, and a bank of lamps .25, ifdes'ired', connected in parallel. with the alarm circuit 23 and'aconductor wire2fi which is connected to the armature 27 of a relay 28. The armature is moved to circuit closing position with a fixed contact 29, as will be presently described. The contact is connected bya wire 30 to the source of current 13. A wire 3| is connected to the wire 2| on the opposite side of the low wattage device 22 from the wire 30 and is connected to one end of the coil of the relay 28. A wire 32 is connected to the other end of the coil and to the ground II.

The coils of both relays are high resistance coils, but an important feature of the invention is that the coil of the relay I4 is of lower resistance than the coil of the relay 28.

An important feature of the invention is that the voltage across the relay 28 will be substantially increased upon opening of the relay l4, due to the low wattage device connected to the relay M, so that the relay 28 will be sufiiciently energized to attract its armature and close the alarm circuit.

In operation, the. current divides at the low wattage device 22 and flows through the coil M of the low resistance relay and through the coil of the high resistance relay 28 so that both coils are simultaneously energized, but the coil of the high resistance relay 28 is not sufliciently energized to move the armature 21 to circuit closing position, and consequently while the protective circuit, [0 remains closed at the contact i9 due to the relay coil i4 attracting the armature IS, the alarm circuit 23 will remain open since the relay coil 28 is not sufiiciently energized to move the armature 21 to circuit closing position against the contact 29.

When the closedcircuit I0 is broken at one of the circuit breakers II, the coil of the relay M will be deenergized and the armature IE will be moved to open circuit position in relation to the The full contact H! by the armature spring'33. voltage current now flows through thecoil ofthe relay 28 and energizes the coil sufficiently to.

move the armature 21 to circuit closing position" with relation to the fixed contact .29-an'd1en-.'f f

scribed that the high resistance electromagnetic coil 28 will be energized to move the armature 21 to closed circuit position against the contact 29 and energize the alarm bell and signal lamps.

From the above description it is thought that the construction and operation of the invention will be fully understood without further explanation.

What is claimed is:

In alarm apparatus, a normally open alarm circuit, an alarm device inthe circuit, a relay having contacts in the alarm circuit and having a coil, a source of electricity grounded on one ergizes the bell 24 and warning lamps 25. The

alarm circuit cannot be opened to prevent sound ing oi the alarm even should the circuit breaker be reset to normal position because the circuit through the coil; of the relay 14 cannot be reestablished to move the armature ifi to circuit 7 closing position until the push button switch I8 v through: the coil of the relay 28 is broken manually, and this is accomplished through the medium of a switch 34 which interrupts the current supply circuit between the source [3 and wire 30.

An open circuit 35 has one terminal connected to that terminal of the ,coil of the low resistancerelay to which the wire [5 is connected, said wire being connected to the switch I8 as above described. The open circuit wire is wrapped around the closed circuit I 0, but is insulated from the latter. Should an attempt be made to sever the closed protective circuit ill by, severing the same by' a knife or other cutting tool, 'the wire 35 will besimultaneously out and since the knife blade must bridge both wires during the cutting operation, the coil M of the relay will be grounded by the blade of the knife bridging the wire35 and closed circuit 'liLwhich latter'is grounded and consequently the armature l6 will drop-to open circuit position with the result as aboveldeside and connected to one of said contacts, a norfi'mally. closed protective circuit grounded at one end and connected to the source of electricity in parallel with'said coil of the alarm circuit relay, fa circuit breaker in, the closed protective circuit. ,a lowwattage device in the closed protective circuit, a normally open protective circuit extending coincident with the closedprotective circuit and insulated irOIl'lythG closed protective circuit; a relay having a coil of. less resistance thanmthe alarm circuit relay c'oil connected to andlocated between said protective circuits and-said source of electricity the second namedrelay having contacts in'the closed protective circuit adapted to be openedby deenergizing' of the coil of the secondnained relay when the closed protective circuit is interrupted at said circuit breaker or when the open' protective circuit issurreptitiously cross connected withs and grounded by the open protective circuit through the medium of a metal cutting tool, and a normally open manually controlled switchc'onnectedto said source of electricity and tofthe coil. of the second named relay in a shunt circuit around the contacts of the second named relay, closing of the manually controlled switchenergizing the coil of the second named relayto reestablish the circuit closing position of the contacts of the second named relay ,and close the closed protective circuit, the arrangement being such that when the closed protective circuit is opened the full voltage from the source of electricity flows through the coil of the first named relay to energizedthe relay and move the contacts thereof into circuit, closing position to energize-the alarm circuit.

1 WILLIAM FOUNTAIN. 

